# # 11 - Due Sunday December 2 2007 11:59 PM EST Description...

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Due: Sunday, December 2, 2007 11:59 PM EST Current Score: 29 out of 30 Question Score Submission Options Description Homework #11 deals with confidence intervals for population means and population proportions in single-sample and two- sample situations and the interpretation of confidence intervals. Instructions Homework #11 You are allowed 5 submissions. Due date is 11:59pm Sunday, December 2. 1. 5/5 points Last Response | Show Details All Responses Notes The NAEP (National Assessment of Educational Progress)test was given to a sample of 1062 women of ages 21 to 25 years. Their mean quantitative score was 275 . Take it as known that the standard deviation of all individual scores is = 56 . a) Give a 95% confidence interval for the mean score in the population of all young women. 271.63 272 to 278.368 278 b) Give the 90% confidence interval for . 272.17 272 to 277.83 278 c) Give the 99% confidence interval for . 270.575 271 to 279.42 279 d) What are the margins of error for 90%, 95%, and 99% confidence? NOTE:

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the margin of error is for 90%, 2.82678 2.83 for 95% 3.368 3.37 for 99% 4.42491 4.43 e) How does increasing the confidence level affect the margin of error of a confidence interval? (_) (_) As the confidence level increases the margin of error does not change. (o) (o) As the confidence level increases the margin of error increases. (_) (_) As the confidence level increases the margin of error decreases. 2. 6/6 points Last Response | Show Details All Responses Notes The NAEP test was given to a sample of 1090 women of ages 21 to 25 years. Their mean quantitative score was = 285 . Take it as known that the standard deviation of all individual scores is = 59 . a) Give a 95% confidence interval for the mean score in the population of all young women. 281.5 281 to 288.5 289 b) Suppose that the same result, = 285 , had come from a sample of 285 women. Give the 95% confidence inteval for the population mean in this case. 278.15 278 to 291.85 292 c) Now suppose that a sample of 3900 women had produced the same sample mean as above. Compute the 95% confidence interval for . 284.05524 283 to 285.94476 287 d) What are the margins of error for the samples of size 285 , 1090 , and 3900 ? NOTE: the margin of error is For 285 : 6.85 6.85 For 1090 : 3.5 3.5
For 3900 : 1.85 1.85 e) How does increasing the sample size affect the margin of error of a confidence interval? (o) (o) As the sample size increases the margin of error decreases. (_) (_) As the sample size increases the margin of error does not change. (_) (_) As the sample size increases the margin of error increases. 3. 4/5 points Last Response | Show Details All Responses Notes The New York Times and CBS News conducted a nationwide poll of 1120 randomly selected 13- to 17- year-olds. Of these teenagers, 695 had a television in their rooms and 172 named Fox as their favorite television network. a) Determine 95% confidence intervals for the proportion of all people in this

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# 11 - Due Sunday December 2 2007 11:59 PM EST Description...

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